Network Printing System, Network Communication Method to Print Information, and Host and Image Forming Device to Perform Network Communications

1. A network printing system, comprising: a mail server to provide a mail transmitting/receiving service; an image forming device to access a mail account allocated to the mail server and receive a mail transmitted to the mail account; and a host to transmit to the mail server a mail including channel information corresponding to a channel established for the host to communicate directly with the image forming device, the channel information including an Internet protocol (IP) address and a communication port of the host, wherein the image forming device attempts to access the host by using the channel information included in the received mail, wherein the host transmits a print data through the channel formed in advance by the image forming device's accessing the host, wherein the image forming device is connected to an internal network, the mail server and the host are connected to an external network, and access to the internal network from the external network is restricted by a firewall.

2. The network printing system of claim 1 , wherein the host comprises: a user interface unit to receive an input of the mail account to transmit the mail and receive an input of the channel information of the host; a mail preparing unit to prepare the mail by using the input mail information and the channel information; and a communication interface unit to transmit the prepared mail to the mail server.

3. The network printing system of claim 1 , wherein the host includes a security code in the mail and transmits the mail with the security code to the mail server.

4. The network printing system of claim 1 , wherein the image forming device comprises: a user manipulation unit to receive an input of an address of the mail server required to receive the mail; a communication unit to access the mail server by using the input address; a mail analysis unit to confirm a channel to provide access to the host, included in the mail if the mail exists in the mail account of the accessed mail server; a control unit to control the communication unit to receive print data by accessing the host through the confirmed channel; and a print engine unit to print the print data received through the communication unit.

5. The network printing system of claim 4 , further comprising: a storage unit to store a security code of a predetermined form; wherein if the security code of the predetermine form exists in the mail, the mail analysis unit confirms whether the security code existing in the mail coincides with the security code stored in the storage unit, and if the security code existing in the mail coincides with the security code stored in the storage unit, confirming the channel information by analyzing the mail.

6. The network printing system of claim 1 , wherein the image forming device comprises: a communication unit to receive the print data from the host by using the channel confirmed through the channel information; a mail analysis unit to confirm whether a security code exists in the received print data, and if the security code exists, confirming whether the security code existing in the print data coincides with a security code stored in the image forming device; and a print engine unit to print the print data if the security code existing in the print data coincides with the security code stored in the image forming device.

7. The network printing system of claim 1 , wherein the host is located in a public network that is an external network, and the image forming device is located in a private network that is an internal network including a firewall.

8. A network communication method to print information, the network communication method comprising: transmitting by a host a mail including channel information corresponding to a channel established for the host to communicate directly with the image forming device, to a mail server allocated with a mail account of an image forming device, the channel information including an Internet protocol (IP) address and a communication port of the host; receiving by the image forming device the mail transmitted to the mail account and attempting to access the host by using the channel information included in the received mail; transmitting by the host print data to the image forming device through the channel formed in advance by the image forming device's accessing the host; and printing by the image forming device the transmitted print data, wherein the image forming device is connected to an internal network, the mail server and the host are connected to an external network, and access to the internal network from the external network is restricted by a firewall.

9. The network communication method of claim 8 , wherein the transmitting of the mail comprises: receiving an input of the mail account to transmit the mail and the channel information of the host; preparing the mail by using the input mail account and the channel information; and transmitting the prepared mail to the mail server that corresponds to the input mail account.

10. The network communication method of claim 8 , wherein the mail that is transmitted to the mail server includes a security code input from the host.

11. The network communication method of claim 8 , wherein the accessing of the host comprises: inputting an address of the mail server required to receive the mail; accessing the mail server by using the input address; confirming a channel established to provide access to the host, included in the mail if the mail exists in the mail account of the accessed mail server; and accessing the host through the confirmed channel.

12. The network communication method of claim 11 , wherein the confirming of the mail comprises: confirming whether a security code exists in the mail if the mail exists in the mail account; confirming whether a security code stored in the image forming device coincides with the security code existing in the mail if the security code exists in the mail; and confirming the channel by analyzing the mail if the security codes coincide with each other.

13. The network communication method of claim 12 , wherein the confirming of the mail further comprises: deleting the mail stored in the mail server if the security codes coincide with each other.

14. The network communication method of claim 8 , wherein the printing of the print data comprises: receiving the print data from the host through the channel; confirming whether a security code exists in the received print data; and if the security code exists in the print data, printing the print data where the security code existing in the print data coincides with a security code stored in the image forming device.

15. The network communication method of claim 8 , wherein the host is located in a public network that is an external network, and the image forming device is located in a private network that is an internal network including a firewall.

16. A host to perform network communications, the host comprising: a user interface unit to receive an input of channel information corresponding to a channel established for the host to communicate directly with the image forming device and a mail account of the image forming device allocated to a mail server, the channel information including an internet protocol (IP) address and a communication port of the host; a mail preparing unit to prepare the mail by using the input mail account and the input channel information; and a communication interface unit to transmit the prepared mail to the mail server that corresponds to the input mail account, and transmit the print data to the image forming device though the channel when the channel with the image forming device is formed in advance by the image forming device's accessing the host, wherein the image forming device is connected to an internal network, the mail server and the host are connected to an external network, and access to the internal network from the external network is restricted by a firewall.

17. The host of claim 16 , wherein the image forming device accesses the mail account allocated to the mail server to confirm the transmitted mail, accesses the host through the channel included in the confirmed mail, and receives and prints the print data from the accessed host.

18. An image forming device to perform network communications, the image forming device comprising: a user manipulation unit to receive an input of an address of a mail server required to confirm a mail transmitted from a host to the mail server; a communication unit to access the mail server by using the input address; a mail analysis unit to extract channel information, included in the mail, used to establish a channel for the host to communicate directly with the the image forming apparatus, when the mail exists in a mail account of the accessed mail server, the channel information including an Internet protocol (IP) address and a communication port of the host; a control unit to control the communication unit to attempt to access the host by using the extracted channel information included in the received mail, and to control the communication unit to receive print data through the channel formed in advance by the image forming device's accessing the host; and a print engine unit to print the print data received through the channel, wherein the image forming device is connected to an internal network, the mail server and the host are connected to an external network, and access to the internal network form the external network is restricted by a firewall.

19. The image forming device of claim 18 , wherein the host prepares and transmits the mail that includes the channel to the mail server that provides a mail transmitting/receiving service, and transmits the print data to the host if the communication channel with the host is formed.

20. A network communication method to print information, the network communication method comprising: accessing by an image forming device through a firewall on a private network an email server located on a public network; retrieving by the image forming device an email including a print request message including an internet protocol (IP) address, a port number, and a security code; matching by the image forming device the security code to a predetermined security code; establishing by the image forming device a connection with a host on the public network through the firewall using the IP address and port number of the host; receiving by the image forming device print data through the firewall; and performing by the image forming device a print operation on the print data.